Medical procedures at times involve implantation of liquid-filled devices in any of numerous portions of a patient's body. Some examples of fluid-filled reservoirs include breast implants, testicular implants, drug-delivery systems, and adjustable gastric bands. In addition, recently there has been much work involving liquid-filled intraocular lenses. These lenses have the advantage that they can be implanted in an unfilled configuration through a small surgical incision; after implantation, the lens can be inflated. Various intraocular lenses may even use a liquid to change the refractive power of the lens or to interact with the natural eye muscles to focus.
In many liquid-filled devices there is a need for a valve that allows access to the internal contents of the implant. In the case of breast implants, the fluid level can be adjusted to change the size of the implant. In intraocular lenses, the amount or type of fluid in the intraocular lens can change its refractive power or how it interacts with the eye. Often, fluidic access to the reservoir of the liquid-filled device is desired not only during implantation but also afterwards, thereby allowing the implant to be filled, emptied, and/or adjusted. Valve leakage is a particular risk in adjustable liquid-filled devices, because leakage from the implant changes the implant properties and can harm the patient. For example, a breast or testicular implant could change size, a drug reservoir may release a pharmaceutical agent into the body, and a gastric sleeve could change the amount of compression applied to the stomach. Leakage from an intraocular lens may cause refractive error or drift, and/or it may result in less interaction with the eye and decreased accommodation.
Accordingly, there is a need for valves compatible with implantable devices and which resist leakage during ordinary use and following fluidic access to the reservoir, both during and after implantation.